Marked pharmaceutical tablet and method of marking the same



Dec. 23, 1958 R. Y. SANDERS, JR 2,855,810

MARKED PHARMACEUTICAL TABLET AND METHOD OF MARKING THE SAME Filed 001;. 7. '1955 INVENTOR. flay X SANDER$,/0.

MARKED PHARMACEUTICAL TABLET AND METHOD OF MG THE SAME Roy Y. Sanders, Jr., Buffalo, N. Y. Application October 7, 1955, Serial No. 539,111

Claims. c1. 16782) This invention relates generally to the-pharmaceutical art, and more specifically to the ink printing of indicia on pharmaceutical tablets.

The importance of providing pharmaceutical tablets with a clearly visible identifying marking, to prevent spurious imitations and substitutions, is well illustrated by the significant volume of business which has been lost by some manufacturers because of such imitations and substitutions. Accordingly, manufacturers have resorted to adding trace elements to their formulae, imparting odd shapes to their tablets, embossing and/or engraving identifying marks on uncoated tablets, and to the use of distinctive colors, to positively identify their product and to combat counterfeiting and substitution.

However, the trace elements are not normally visible, the use of particular shapes and colors is not always satisfactory because they are too easily duplicated, and conventional embossing and engraving techniques of marking have certain disadvantages and furthermore are not particularly suitable for use with coated tablets of the type which have a medicinal core covered with successive undercoats, smoothing coats and finishing coats.

In addition, coated tablets must be pharmaceutically elegant if they are to enjoy consumer approval, and any identifying marking used therewith must not detract from the pharmacetuical elegance of the finished product.

In my'pending application Ser. No. 333,147, I disclose a pharmaceutical tablet marking technique wherein ink indicia is printed on the coated medicinal core beneath an outer coating of transparent material. covering the coated core and the indicia printed thereon. I also disclose therein the specific technique of printing the mark on a coating having a resin base, such as shellac, with an ink having the same resin base. This technique provides a marked tablet possessing the requisite pharmaceutical elegance and wherein the marking is protected and therefore not subject to being chipped or flaked off during handling.

However, if the resin base comprises, for example, straight shellac, certain difiiculties are likely to be experienced because the shellac coating tends to stick to the wall of the coating pan, and to pull off the sugar coating around the medicinal core in the process. Also, the shellac coat tends to remain a little tacky whereby the shellac coated tablets do not always feed properly into the printing machine, and do not always seat properly in the machine for receiving the printing roller. In addition, the shellac coating tends to set in a manner precluding the desired bond between it and the indicia printed thereon.

These various difliculties are inconvenient and detract from the pharmaceutical elegance of the finished tablet, and are apt to cause a relatively high number of rejects and thereby increase manufacturing costs.

Accordingly, it is a primary object of this invention to provide a tablet coating particularly adapted to receive the contemplated ink printing and which avoids the foregoing difliculties.

** tent O A marked pharmaceutical tablet in accord with this invention is characterized in one aspect thereof by the provision of a resinous coating, over the coated medicinal core, containing a lubricative plasticizer, the mark being printed thereon with an ink preferably having the same resin base, and, in the presently preferred form, a transparent protective coating over the coated core and the mark.

In another aspect thereof, a pharmaceutical tablet marked in accord with this invention is characterized by the process which comprises drying the resinous coating and, before it sets, printing the mark on the resinous coating and then drying both the ink printing and the resinous coating until they set before the protective coating is applied.

The foregoing and other objects, advantages and characterizing features of my invention Will become clearly apparent from the ensuing detailed description, taken together with the accompanying drawing forming a part thereof wherein:

Fig. 1 is a top plan view of a pharmaceutical tablet marked in accord with my invention, certain parts being broken away for greater clarity; and

Fig. 2 is a transverse sectional view taken about on line 11-11 thereof.

Referring now to the accompanying drawing, in the presently preferred form of my invention the tablet, generally designated 1, comprises a conventional medicinal core 2 which is coated in a known manner with the usual subcoats comprising, for example, a mixture of gelatin, sugar and dusting powder until the corners of the core are well covered and the tablet is well rounded and in proper proportion, smoothing coats comprising, for example, a white undercoating or grossing syrup for white tablets, or a plain coating syrup for colored tablets until the tablets are well rounded and smooth, and finishing coats comprising, for example, either plain or colored coating syrups. While the foregoing constitute, in reality, a large number of coats, for simplicity and ease of illustration I show them combined into a single coat 3, and this is what is referred to herein by the term coated medicinal core.

In accord with this invention, the coated medicinal core 2, 3 is covered with a resinous coating 4, containing a lubricative plasticizer, the indicia marking 5 is ink printed on the coating 4, and the coating 4 and marking 5 preferably are covered with a transparent protective coating 6.

More specifically, in a preferred embodiment of my in' vention the indicia 5 is ink printed on a resinous coating 4 having a shellac base, such as dewaxed shellac dissolved in alcohol, to which there is added a lubricative plasticizer which is edible, soluble in alcohol, and compatible with the shellac, such as long chain higher molecular weight fatty alcohols, for instance stearyl alcohol or 'cetyl al-' cohol, or the glycerides of the higher fatty acids, such asthe monoglycerides or acetylated monoglycerides in the ratio of from 3% to 10%, and preferably about 8%;

based on the weight of the dry shellac. Triglycerides of fatty acids also can be used, although it is believed that they are not as satisfactory as those plasticizers listed above.

This resinous coating 'is applied to the coated tablet Patented Dec. 23,1958- in a machine having an endless conveyor with rows of spring-backing pockets receiving the tablets from a feed hopper and conveying them beneath a printing roller to a discharge chute.

The resinous coating 4 of this invention is particularly suited to printing in this manner because the lubricative plasticizer in the coating makes the tablets lubricous whereby they feed easily from the feed hopper onto the conveyor, and readily nestle and center themselves in the conveyor pockets. Therefore, the number of tablets which stick together, jam and break as they are fed into the printing machines is greatly reduced, and a large number of tablets are properly aligned to best receive the printing, as compared to the case where an essentially straight shellac coating is used, whereby the percentage of rejects due to these causes is greatly reduced.

Also, the plasticizer delays setting and hardening of the resinous coating, thereby facilitating the printing of the mark before the coating 4 sets and becomes brittle. The ink printing adheres, or takes, much better when the resinous coating 4 is somewhat plastic and not brittle, and therefore in accord with my invention the mark is printed on the coating 4 after it has partially dried and before it has set.

It is preferred that the mark be printed with an ink having the same resin base as the coating 4. Thus, where dewaxed shellac forms the base for the coating 4, shellac preferably is the base for the ink, the shellac being carried in a suitable spirit solvent such as the lower aliphatic alcohols, for instance ethyl alcohol. This is deemed particularly advantageous because the alcohol in the ink tends to cut or dissolve the coating 4 and the shellac in the ink adheres to the shellac of the coating to give a very good bond between the ink indicia mark and the coating.

It is another feature of my invention that the resinous coating containing the lubricative plasticizer is particularly advantageous because it provides the desired tablet smoothness and lubrication, and even more as previously noted, all without impairing the bond between the ink indicia and the coating, and other possible disadvantages such as, for example, tablet sticking, which might occur if, for example, a waxy coating were used to provide the desired smoothness. Indeed, one reason for limiting the maximum amount of plasticizer to about based on the weight of the dry shellac, is because any substantial increase in plasticizer beyond this amount tends to make the coating too plastic and too waxy for proper setting thereof and printing thereon.

Another advantage of this coating is found in its substantial transparency and high gloss, whereby it does not noticeably alter the appearance of a color coat therebeneath but preserves and even enhances the pharmaceutical elegance thereof, although I do not mean by this statement to preclude the possibility of applying color to the coating 4. The indicia is printed on the resinous coating in ink of a distinguishing color, as compared with the color coats, and the ink printing will adhere to this coating with such tenacity, and the coating is of such pharmaceutical elegance, that in some instances it might be considered unnecessary to provide an outer coat thereover.

After the indicia is printed, the marked tablet is dried until the coating 4 and the indicia have set, which can take several days if forced drying is not used. This is to ensure that the mark will adhere to the resinous coating and not smudge or rubofi during the polishing operation or upon handling if the polishing step is omitted.

This last step, which might not always be necessary in the case of this invention, consists of applying the transparent, and preferably polished, outer coat 6 which can comprise carnauba wax, beeswax, or the like, over the coating 4 and indicia S, which can be done in polishing pans of known type. The advantages of the polished coat 6 is that it adds to the polished and pharmaceutically elegant appearance of the marked tablet, and protects the indicia 5 against rubbing, chipping or flaking off upon contact with other tablets, or with its container, during handling thereof.

Thus, my invention fully accomplishes the aforesaid objects, and provides a pharmaceutically elegant medicinal tablet having ink indicia printed thereon for purposes of identification and the like.

I do not intend to be limited to the specific details and examples given herein by way of example, but instead I intend that my invention be defined by the appended claims.

While only shellac has been specifically disclosed as the base for the resinous coating 4, the term resinous as used herein and in the claims is meant to include other edible, non-toxic, film forming resins such as for example the epoxy resins, sandarac, and indeed any resin suitable for tablet coating.

Having completely disclosed and fully described my invention, what I claim as new is:

1. A marked pharmaceutical tablet for internal consumption comprising, a coated medicinal core including a plurality of foundation subcoats, a resinous coating containing a lubricative plasticizer over said core, and indicia printed on said coating in ink of a distinguishing color.

2. A pharmaceutical tablet for internal consumption having an identifying marking thereon comprising, a coated medicinal core including a plurality of foundation subcoats, a first coating having a resin base and containing a lubricative plasticizer over said coated core, indicia printed on said first coating in ink of a distinguishing color, and a transparent second coating over said first coating and said indicia.

3. A pharmaceutical tablet for internal consumption having an identifying marking thereon comprising, a coated medicinal core including a plurality of foundation subcoats, a resinous coating containing a lubricative plasticizer over said coated core, and indicia ink printed on said resinous coating.

4. A pharmaceutical tablet as set forth in claim 3, wherein the resin of said coating comprises shellac, and wherein said lubricative plasticizer is a higher fatty alcohol.

S. A pharmaceutical tablet as set forth in claim 3, wherein the resin of said coating comprises shellac, and wherein said plasticizer is a higher fatty glyceride.

6. A pharmaceutical tablet as set forth in claim 3, together with a protective coating over said resinous coating and said indicia.

7. A marked pharmaceutical tablet for internal consumption comprising, a coated medicinal core including a plurality of foundation subcoats, a coating having a resin base and containing a lubricative plasticizer over said coated medicinal core, and indicia printed on said coating in ink of a distinguishing color, said ink having the same resin base as said coating.

8. The method of marking a pharmaceutical tablet having a coated medicinal core including a plurality of foundation subcoats which comprises, covering said medicinal core with a resinous coating containing a lubricative plasticizer, partially drying said resinous coating, ink printing the marking on said resinous coating before it has set, and drying the marked product until the ink marking has set.

9. The method of marking a pharmaceutical tablet having a coated medicinal core including a plurality of foundation subcoats which comprises, covering said coated core with a resinous coating containing a lubricative plasticizer, partially drying said coating, printing the marking on said coating before it has set in ink of a distinguishing color, drying said coating and said marking until they have set, and then covering the marked tablet with a transparent outer coating.

10. The method of marking a pharmaceutical tablet as set forth in claim 9, followed by polishing said outer coating.

11. A marked pharmaceutical tablet for internal consumption comprising, a coated medicinal core including a plurality of foundation subcoats, a resinous coating containing a higher fatty alcohol lubricative plasticizer over said core, and indicia printed on said coating in ink of a distinguishing color.

12. A marked pharmaceutical tablet as set forth in claim 11, wherein said coating has a shellac base, and wherein said indicia is printed thereon in ink having a shellac base in a spirit solvent therefor selected from the lower aliphatic alcohols.

13. A marked pharmaceutical tablet for internal consumption comprising, a coated medicinal core including a plurality of foundation subcoats, a resinous coating containing a higher fatty glyceride lubricative plasticizer over said core, and indicia printed on said coating in ink of a distinguishing color.

14. A marked pharmaceutical tablet as set forth in claim 13, wherein said resinous coating has a shellac base, and wherein said indicia is printed thereon in inkhaving a shellac base in a spirit solvent therefor selected from the lower aliphatic alcohols,

- References Cited in the file of this patent UNITED STATES PATENTS 200,589 Warner Feb. 19, 1878 2,089,209 2,128,973

Tisdale et al. Sept. 6, 1938 Bernstein June 10, 1941 OTHER REFERENCES Clarkson: Tablet Coating, Drug and Cos. Ind., New York, N. Y., 1951, page 57.

Rowell: The Art of Coating Tablets, Drug and Cos. Ind., vol. 63, No. 4, October 1948, pp. 459, 460, 549, 550 and 551.

Clarkson: Tablet Coating (New York., N. Y., 1951), pp. and 48-50.

Arends: Die Tablettenfabrikation (Berlin, 1950),

Keufrel et al Aug. 10, 1937 i 

1. A MARKED PHARMACEUTIACL TABLET FOR INTERNAL CONSUMPTION COMPRISING, A COATED MEDICINAL CORE INCLUDING A PLURALITY OF FOUNDATION SUBCOATS, A RESINOUS COATING CONTAINING A LUBRICATIVE PLASTICIZER OVER SAID CORE, AND 